Process of revivifying brucite or magnesium hydroxide



Patented June 19, i934 i J PRooE ss OF v.11963493 REVIVIFYING' BRUCITE MA NESI M HYDROXIDE 5 mild-sen o. mggingn; West Los Angeles, Calif.,

- and Franklin T Gardner, Tulsa, Okla.

' No Drawing; Application 'September 16 931,

' Serial-No. 563,220

- The present invention relates to a pro'cess'ro the revivification of brucite or magnesium hy droxide that has been employed in the purifica tion of hydrocarbons such, for example, as

cracked gasoline or its equivalent. 4

The process is particularly directed to the treatment of brucite, or other forms of magnesium hydroxide, particularly such as is described in connection with copendingpatent application.

of Emerson'C. Higgins, Jr. and Franklin T. Gard-- ner, Serial No. 543,004, filed June 8, 1931 One of the objects of the present invention is to remove, from the used brucite, silica, silicates or silicic acid that form within and on the sur-- face of the particles of the brucite during the reactions which take place when gasoline orpther,

similar hydrocarbon material is passed over the same for the purpose of rendering said hydrocarbons sweet to doctor.

In the said above mentioned copending application there has been described a process which,

in essence, consists in treating a hydrocarbon;

such as gasoline so as to modify the therein containedmercaptans, thereby rendering the treated. gasoline or other hydrocarbontsweet to doctor, 'so that it may be readily merchantable. In the said process the gasoline or other hydrocarbon is.

passed, in admixture with Y sulphur dissolved thereirn'upwardly through a bed of comminuted' brucite or through artificial magnesiumhydrox- "ide. In the presence of the sulphur, the mercaptans in the gasoline or other hydrocarbons,

react, with the magnesium hydroxide or brucite to finally form organic .disulphides. Durin the course of 'this process thebrucite gradually loses its efficacy and becomescoated and permeated.

with silicates, 1 or more particularly with free silicic acid. This silicic acid is derived from the.

silicates present in the natural brucite andother forms of magnesium hydroxide, which silicates usuallyconsistof those of iron, magnesium, calcium, aluminum, potassium, etc. 7 While the presence of. these silicatesinthe fresh, or unused, brucite. does notinterfere materially with the operation of the sweetening; as disclosed in the said copending application, the reactions taking place during the, said operations do, however, decompose these silicates with the formation ofthecorresponding sulphides or sulphates of free'silicic acid. The latter-is a very gelatinous material and deposits. itself upon-the surface of the-brucite, thereby retarding the efiicacy. off-the, latter, so that, as the operation of, purifying the,

gasoline proceeds, the brucite gradually, loses its eificacy and thus brings about the requirement for itsrevivification. U 7

There has been described,- in the said copending application, a comparatively simple process of brucite reviviflcation, which consists in the the. said metals and the'liberationof treatment of the brucite with either hot'orcoldwater and or steam for the removal of the soluble sulphides or sulphates therefrom. While this treatment withhot waterservesfor the removal of water-soluble"materials, it will not remove the free silicic acid, for the reason that the latter is.

not readily soluble in water. r I v The specific object of the present invention, therefore, is the removal oi this gelatinous silicic acid that remains upon the brucite. Itis known that silicic acid is s'o lubleflin concentrated aka-i1- line' solutions, but dilute solutions of alkalies may be employed provided that elevated temperatures are employed. It has-been found that very excellent results can be obtained bvthe useoi av 2.5% solutionlof caustic soda (sodium hydroxide NaOH) Approximately the temperature of boiling water is used during the first stage of re vivification off the brucite, when performed ac; cordance with the present invention. .IItFis not. necessary toremove the brucite from the towers in which it is stored duringthe gasoline sweeten.- ing process disclosed in .the copendingapplic a-f tion, Serial No. 543,004,515 the revivifying treatment can be carried out in saidtower itself. It is effected as follows: I I

After the gasoline or other hydrocarbon has been displaced by a slowly rising column of water; 9 a to ive eh mca e n 9. the ower ahead of it, --the water is thenwithdrawn and st es -wm m y 9 contai su stantially 2 5 by weight of 'g sodium hydroxide, NaOH, isforced into the botto m of the tower;

until the entire mass of brucite is submerged.

e. ni ein ltew is jt snheat to b i in by means of. aclosed steam coil, the design,

andfurther purpose of which .is ihereinafter Idethecausticsoda solution,; now containing a so-.

utie r o um s li a s d w o t he. tower. Following this, the br'ucite inthetower is then washed with hot water I to remove the soluble sulphates'or sulphides which may have escaped solution duringthe previous treatment; The water which is used after the removal'ofthe sodium silicate solution is allowed to act upon the brucite for 31:0 4 hours'and .is then drawn ofiQ 'It is within .the scope of thepresent invention to repeat this washing operation; with hot water, or merely to rinse the brucite :once or twice so as to insure th e removal ofas much aspossible of the adheringsolution. v After the wash-water has been-drainedirom the tower, hot or cold airis passed through the mass of brucitejto assistindrying-the same. Each tower is equipped with a closed coil, through which either live or exhaust steam is passed.

This coil is designed and located in the tower so as to obtain the most effective drying of the brucite. After the brucite is dried, it is ready for re-use, and fresh quantities of gasoline to be purified may then be passed through the same; in the manner disclosed in the already mentioned copending application, Serial No. M3904, filed June 8, 1931.

Experiments have demonstrated that after the revivification of a given mass of brucite has been efiected three or four times with the use of the caustic sodium solution, there will be practically no more silicates present in the brucite, and the brucite may then subsequently be re vivified for use merely by the expedient of washing it with hot water and subsequent drying asset forth in the said copending application. It has also been found that such desilicalized brucite is much more eflicient than the natural brucite, and it is within the scope and intent of the present invention to subject natural brucite to a treatment with caustic soda in the manner above described for the purpose of rendering the same more active than it would other- Wise be for effecting the sweetening and neutralization of hydrocarbons.

However, itis more economical to depend upon the reaction between the impuritiesin the gasoline or hydrocarbon and the silicates in the natural brucite, rather than to expend time and reagents to remove these before initially using the brucite. If this is desired, however, brucite may be treated with a strong acid to convert the therein contained silicates into free silicic acid, following by washing to remove the salts formed thereby, and then to remove the thus liberated silicic acid by means of" a solution of a caustic soda in the manner already'hereinabove set'f-orth.

While a solution of caustic soda is the most economical and generally available for effecting the; removal of the gelatinous silicic acid from the brucite, it will, of course, be obvious to a skilled chemist that a similar reaction will take place if said gelatinous silicic acid be subjected to the action of one of the other elements of the alkali groups ofwhich lithium is the first member, the others being sodium, potassium, caesium and rubidium. It is therefore within the intent and scope of the present invention to employsuch other alkalies and particularly potas sium hydroxide, which insome parts of the worldis; available at a cost not very much higher than that of'; sodium hydroxide. For practical purposes, however, the other alkalies in this group,

while capable of performing the function of 'removing the'silicic acid from; the brucite, are too expensive at the present time for commercial exploitation.

While the operations are most economically carried; out in the tower in which the brucite has been used for effecting the sweetening of gasoline or other hydrocarbons, it will, of course,

be within the scope of' the present invention toperform said operations outsideof said tower after removing the brucite from the tower intolute alkaline solution of the type of sodium hydroxi-d'e solution while under superatmospheric temperature to effect the removal of silicious matter therefrom.

2; The process of treating brucite which comprises subjecting the, same to the action of a boiling solution of the hydroxide of a metal of the alkali group to remove silicious matter therefrom.

3. The process of treating brucite which comprises subjecting the same to the action of a boiling, solution of sodium hydroxide to remove silicious matter therefrom.

4. The process of revivifying spent brucite which has been employed in the purification of hydrocarbons which comprises boiling the same with an alkaline solution, then withdrawing said solution, then boiling the brucite with water, withdrawing the water, and drying the brucite.

5. The processof revivifying spent-magnesium hydroxide employed inthe sweetening of hydro-- carbons by which sweetening the magnesium h-ydroxide becomes inactivated by deposition of salts andsi-lici'cacid thereon, which comprises converting said silic-ic acid into a soluble compoundthereof, and dissolving saidcompound bymeans ofwater, withdrawing the resulting solution and drying the magnesium hydroxide.

6. The process of revivifyingspent magnesium hydroxide which has become inactive byyeontact with impure hydrocarbons due tothe deposition of silicic acid thereon, which comprises the stepof subjecting said magnesium hydroxide to the action of a caustic alkali".

7. The process of revivifying spent'magnesium hydroxide which has been employed in the purification of hydrocarbons which comprises: treatits ing the spent magnesium hydroxide" contam-inated with silicicacidwith a dilute alkaline solution whereby contained silicic acid: is converted into a water soluble silicate, then separating thesilicate from the hydroxide by washing with water;

8. The process of enhancing the purifying powerof brucite for hydrocarbons which coinprises converting thesilica-tes naturally contained in the brucite into metallic salts and free silicic acid by heating the brucite with a strong acid capable of causing such con-version Without affecting the brucite, converting the silicic acid intoa water soluble silicate by the contact therewith of'a hydroxide of a metal of thealkali group, then washing the thus. formed silicate out from" the brucite with water.

9. The process of enhancing the purifying power of brucite for hydrocarbons. which com=-- prises. converting the silicates naturallycontainedv in the brucite intometallic salts andf-ree sil'ici'c acid byheating thebruci-te with a strong acidcapable of= causing suchconversion without affecting thebrucite, converting the silicic acid into a water soluble sodium-silicate by the contact therewith of sodium hydroxide, then washing the thus. formed silicateout from the-brucite with water;

10: The process of revivifyingspent magnesium. hydroxide which has become inactive by contact. with impurehydrocarbons clue to thedeposition. of" silicic acid thereon which comprises the step. of-' subjecting said magnesium; hydroxide to the action of: a solution of sodium-hydroxide of about 215% concentration.

EMERSON G. HIGGINS, JR. FRANKLIN T. GARDNER". 

